It is found that the conventional mask simply utilizes a visor to separate the face of an user from the outside and enables air to flow in the nose of the user from the lower side of the visor. However, much mask have no filtering effect and cannot keep the user form being hurted by the polluted air. As to the cloth mask, it will obstruct the user from inhaling and exhaling normally thus making the user have a slight oxygenless sign.
Therefore, it is an object of the present invention to provide a helmet which may obviate and mitigate the above-mentioned drawbacks.